Our objective to develop non-invasive visual function tests to improve the detection and diagnosis of glaucoma at the earliest stages of the disease. The visual function tests being evaluated are measures of color perception outside of the usual areas for such tests. Rather than studying color vision at the center of the visual field, we are looking at color contrast and spectral sensitivity functions in more peripheral locations in the visual field. Color contrast perimetry involves the use of variably colored test lights produced by a microcomputer controlled color video device, while peripheral spectral sensitivity tests measure the sensitivity for detection of variably colored test lights in the presence of strongly color adapting surrounds. Prior study of color vision defects in patients with glaucoma have suggested that damage to the perception of blue/yellow color contrast may occur prior to the onset of glaucomatous damage detectable by conventional (perimetric) forms of testing. The specific aims of this proposal are: (1) To prospectively evaluate the sensitivity of extrafoveal tests of color vision for the detection of earliest glaucomatous visual field defects in a population of patients known to be at high risk; (2) To test the hypothesis that glaucomatous visual field defects detected by extrafoveal tests of color vision antedate the appearance of defects as mapped by conventional threshold static perimetry. Efforts to improve the sensitivity and specificity of techniques used to diagnose the earliest stages of glaucoma are being sought so as to improve the chances of preventing irreversible loss of vision in patients who ultimately develop the disease. There is a need for improved techniques of early diagnosis since current methods allow detection of the disease only at a relatively advance stage. Once the disease is established, and in spite of the best available medical and surgical therapy, there remains a disturbingly high incidence of inexorable loss of vision. It is hoped that by improving the sensitivity of early diagnosis of the disease, that appropriate therapy can be instituted for affected individuals at an earlier stage, increasing the likelihood of preservation of vision over the subsequent course of the disease.